Q to (Lake) Bandwidth converter

Michael John

Jun 25, 2011
Sydney, Australia
The difference in DSP processor's interpretation of Q and bandwidth has frequently been raised. (I think Bennett wrote an article on this some time back.)

Attached is a spreadsheet (written in the Dolby Lake days) for converting Q into the BW (bandwidth) value for biquad-based parametric filters in the XOVER and AUX tabs in the Lake controller. (The original posting can be found on the old Dolby Live Sound Forum Q To Bandwidth Converter - Knowledge Base - Dolby Live Sound Forum.)

View attachment Lake_Q_to_BW_Calculator.xls

This was often a starting point when migrating DSP presets into Lake processors. (My understanding is that it's still relevant for the new Lab Gruppen amps and processors.) I must stress "starting point" for a number of reasons. A filter defined for one sample rate may have a different response if entered into a processor running at a different sample rate (e.g. 48 versus 96 kHz). Also I've heard Q is sometimes interpreted differently by different processors. And, this spreadsheet doesn't deal with shelf filters. It's always good to verify with measurements.

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